Increase Content field size of gpg_key and public_key to MEDIUMTEXT (#20896)

Unfortunately some keys are too big to fix within the 65535 limit of TEXT on MySQL
this causes issues with these large keys.

Therefore increase these fields to MEDIUMTEXT.

Fix #20894

Signed-off-by: Andrew Thornton <art27@cantab.net>

models/migrations/v225.go

@@ -0,0 +1,29 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package migrations
+
+import (
+	"code.gitea.io/gitea/modules/setting"
+
+	"xorm.io/xorm"
+)
+
+func alterPublicGPGKeyContentFieldsToMediumText(x *xorm.Engine) error {
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	if setting.Database.UseMySQL {
+		if _, err := sess.Exec("ALTER TABLE `gpg_key` CHANGE `content` `content` MEDIUMTEXT"); err != nil {
+			return err
+		}
+		if _, err := sess.Exec("ALTER TABLE `public_key` CHANGE `content` `content` MEDIUMTEXT"); err != nil {
+			return err
+		}
+	}
+	return sess.Commit()
+}